An essential component of today's shifting transmissions is the clutch release mechanism, with the aid of which, a clutch with start-up and shifting capabilities in a motor vehicle, can be automatically or manually activated. Such a clutch release device has been made known by DE 694 07 681 T2, wherein a release bearing, affixed to a release flange which, in turn, is fastened to a housing, can be guided in an axial, sliding motion. In addition to this, between said release flange and release bearing, a bearing is interposed, which can allow an effortless, axial sliding action with very little friction.
In the case of this known clutch release device, there are to be found on the radially, inward facing side of said bushing, axially directed, load bearing sections are installed which, by means of axially parallel grooves, are separated from one another. Further information regarding these said grooves, in particular, concerning their width, depth, number and arrangement on the inner circumference of the bushing, is not to be found in this present document in any exact accuracy.
Moreover, it is universally known, that bushings, as a rule, are made of plastics and can be impressed into or integrally joined within a release device housing.
A release lever acts upon a release bearing of such a clutch release device with a releasing force FA, in such a manner, that the pivotal movement of said release lever is converted into a linear motion of the release bearing on the release flange.
Because of frictional intervention and an eccentric point of application for the force between the release lever and the release bearing which, from a practical standpoint, cannot be avoided on both the release lever and the release bearing a tilting moment MV of a greater or lesser force is generated. The magnitude of the force changes in dependency of the sliding position of the release bearing on the release flange.
A tilting force FV acts to create this tilting moment MV, which force acts through the release bearing. That is to say, the bearing bushing thereof acts upon the release flange and there brings about an increase of friction in a longitudinal direction of the release bearing so that motion of the release bearing on the release flange is obstructed and thereby the activation of the clutch is hindered.
Even if, simultaneously, this additional frictional force on the respective clutch behavior may be small, relatively speaking. Nevertheless, during the operational life of such a known clutch release device, this leads to an additional abrasion of the release bearing. That is to say, frictional wear on the bushing as well as on the release flange. As a matter of fact, investigations directed to this very problem, on generically related clutch release devices have shown that the bushing of the release bearing “digs in” to the release flange, because of the above described effects. This leads to a self-obstruction of the release flange which, in turn, extends itself to the bushing thereof which is itself located on the release flange. Where shifting transmissions are concerned, these disturbances in the activation movements of a clutch release device bring about activation and comfort problems in the course of startup, maneuvering and shifting procedures.
With this background, the purpose of the invention is to develop a generic clutch release device so that, in spite of an eccentric point of application of force between the release lever and the release bearing, no abrasive wear related to a moment of tilt exists between the release bearing, i.e., the bushing, and the release flange.